Oscillating looper for sewing-machines



(Model.)

T. G. ROBINSON.

OSGILLATING- LOOPER FOR SEWING MACHINES. No. 316,065.

Patented Apr. 21, 1885.

NrTEn STATES PATENT EETCE.

THOMAS C. ROBINSON, OF BOSTON, ASSICrNOB OF ONE-HALF TO E. B. WELCH, OFCAMBRIDGE, MASSACHUSETTS.

OSClLl .AT|NG LOOPER FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 316,065, dated April21, 1885.

Application led March 27, 1884. (Model.) v

To all whom it may concern:

Be itknown that I, THOMAS O. ROBINSON, of Boston, in the county ofSuffolk and State of Massachusetts, have invented certain Improvementsin Oscillating Loopers or Hooks for Sewing-Machines, of which thefollowing isa specification.

The invention has for its object to provide certain improvements in theform of the hook of a chain -stitch sewing-machine, whereby said hookwhen opening the loop for the suceeeding stitch is prevented frompulling said loop or increasing the tension of the thread.

Of the accompanying drawings, forming a part of this specification,Figure l represents a side elevation of part of a sewing-machine havingmy improvements. Fig. 2 represents an end view ofthe same. Figs. 3 and 4represent perspective views of the improved hook, showing it indifferent positions. Figs. 4fL and 4b represent modifications. Fig. 5represents an end view of a hook of old form.

The same letters of reference indicate the same parts in all thefigures. a represents the hook of a chain-stitch sewing-machine, saidhook operating in the usual manner in catching the needle -thread andopening it while the succeeding stitch is made through the loop thusafforded. The hook, as usual, has two prongs, 2 3,' connected by a neck,4, with the shank 7, which is secured to the oscillating arbor d',whereby the hook is operated as usual.

Heretofore the side of the neck 4 on which the loop slips while it isbeing thus openedviz., the side nearest the prong 2-has been so formedthat it will exert a constant strain or pull on the thread while openingthe loop, thiseffect being due to the fact that the side of the neck 4on which the thread bears and slips during the loop-opening movement asheretofore formed is receding during said movement from the materialwith which the loop is engaged, and therefore constantly tightens theloop, as shown in Fig. 5. rlhe result is that the tension of the threadis widely varied, being at times slack and at other times excessivelytight 5 hence imperfect stitching is produced, and breakage of thread is5o liable to occur. In making my improved a' ofthe hook proper in asingle curve con- 6o l tinuous from the point 2 to the end of the hookat 4, so that as the hook moves to open the loop the distance betweenthe point in the work from which the loop-passes, and any part of theside of the neck along which it slips while being opened will not begreater to any considerable extent than the original length of the loopwhen the prong 2 first enters it. This form enables the loop to remainin a substantially loose condition while 7o it is being opened. It willbe seen that the form of the side of the neck to produce this result, oran approximation thereto, may be considerably modified. I prefer theform shown in Figs. 2, 3, and 4, in which the loop- 75 opening side ofthe neck has a gradual curve or recess, 6, extending from the point ofthe prong 2 to a point at the opposite side of the center of rotation(via, the center ofthe shank 7) from said prong. Whenthehookis at'theex- 8o treme of its loop-opening movement, as shown in Fig. 2, the loopis contained in the inner part rof the recess 6. Vhile this form is thebest of any I have devised, I do not limit myself to the depth of therecess 6 shown, nor to the exten- 8 5 sion of the said recess beyond thecenter of the shank. Figs. 4fL and 4b show the recess 6 made of lesserdepth than in the iigures above described, the recess being carriedabout to the center of the shank but not beyond in 9o a continuouscurve. The hook thus improved moves from one position to the otherwithout causing strain on the loops by either of its movements, the hookslipping easily through the loops but not tightening them.'

It will be understood that the leading prong ofthe hook is oiiset fromthe plane of the body, as usual in looper-hooks, and shown clearly inFig. l.

I claim-- IOO lia

The improved doublepointed looper or osl to this specification, in thelpresence of two oillating hook for chain-stitch sewing-masubscribingWitnesses, this 21st day of March, 1o ehines, having one point deflectedfrom the 1884. plane of the other and having its side a formed T 5 in a.single continuous curve from the point 2 THOMAS C ROBE' SON to therecess which terminates the hook prop- Witnesses: er, substantially asshown and described. .0. F. BROWN, In testimony whereof I have signedmyname A. L. WHITE.

